Sensor with electrical contact protection for use in fluid collection canister and negative pressure wound therapy systems including same

ABSTRACT

A sensor for use in a canister for fluid collection, the canister having a canister top and defining a fluid collection chamber. The sensor includes a first electrode and a second electrode. The first electrode includes a first portion and a second portion, wherein the first portion of the first electrode is supported by the canister top, and the second portion of the first electrode is configured to extend into the fluid collection chamber. The second electrode includes a first portion and a second portion, wherein the first portion of the second electrode is supported by the canister top, and the second portion of the second electrode is configured to extend into the fluid collection chamber. The sensor also includes an electric circuit configured to detect an electrical property associated with the first and second electrodes.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/471,789 filed on May 26, 2009, which claims priority to U.S.Provisional Patent Application No. 61/090,782 filed on Aug. 21, 2008,entitled “WOUND THERAPY SYSTEM WITH CANISTER FILL DETECTOR”, thedisclosures of which are herein incorporated by reference in theirentirety.

BACKGROUND

1. Technical Field

The present disclosure relates to negative pressure wound therapysystems and, more particularly, to a sensor with electrical contactprotection for use in a fluid collection canister and negative pressurewound therapy systems including the same.

2. Description of Related Art

Negative pressure therapy, also known as suction or vacuum therapy, hasbeen used in treating and healing wounds. Treating an open wound byapplying negative pressure, e.g., reduced or sub-atmospheric pressure,to a localized reservoir over a wound has been found to assist inclosing the wound by increasing blood circulation at the wound area,stimulating the formation of granulation tissue and promoting themigration of healthy tissue over the wound. Negative pressure therapymay also inhibit bacterial growth by drawing wound fluids from the woundsuch as exudate, which may tend to harbor bacteria. Negative pressuretherapy can thus be applied as a healing modality for its antiseptic andtissue regeneration effects. This technique has proven effective fortreating a variety of wound conditions, including chronic orhealing-resistant wounds and ulcers, and is also used for other purposessuch as post-operative wound care.

Generally, negative pressure therapy provides for a wound covering to bepositioned over the wound to facilitate suction at the wound area. Aconduit is introduced through the wound covering to provide fluidcommunication to an external vacuum source, such as a hospital vacuumsystem or a portable vacuum pump. Atmospheric gas, wound exudate orother fluids may thus be drawn from the reservoir through the fluidconduit to stimulate healing of the wound. Generally, a fluid collectioncanister for collecting fluids aspirated from the wound is positioned inthe suction line between the wound covering and the vacuum source.Exudate drawn from the reservoir through the fluid conduit may thus bedeposited into the collection canister, which may be disposable.

The fluid collection canister of the wound therapy system may need to bedisconnected or replaced for a variety of reasons, such as when filledwith exudate. A mechanism for preventing overfilling of the collectioncanister may prevent fluid contamination of various components of thenegative pressure wound therapy system and help to prevent spillage orleakage. During a treatment, the collection canister may be preventedfrom overfilling by a hydrophobic filter at the top of the collectioncanister that shuts off the air flow to the vacuum source when thecollection canister is full. During some treatments, the collectioncanister is replaced or emptied of exudate on a regular scheduled basis,e.g., every few days or so. The collection canister may fill morequickly than anticipated. If this occurs, therapy cannot be delivered tothe wound until the collection canister is emptied or replaced. There isa need for a negative pressure wound therapy system that is capable ofproviding an indication to alert the user that the collection canistermust be emptied or replaced.

SUMMARY

The present disclosure relates to a sensor for use in a canister forfluid collection, the canister having a canister top and defining afluid collection chamber. The sensor includes a first electrode and asecond electrode. The first electrode includes a first portion and asecond portion, wherein the first portion of the first electrode issupported by the canister top, and the second portion of the firstelectrode is configured to extend into the fluid collection chamber. Thesecond electrode includes a first portion and a second portion, whereinthe first portion of the second electrode is supported by the canistertop, and the second portion of the second electrode is configured toextend into the fluid collection chamber. The sensor also includes anelectric circuit configured to detect an electrical property associatedwith the first and second electrodes. The second portions of the firstand second electrodes may be at least partly covered with a coating toinhibit encrustation formed by drying of exudate. The sensor may alsoinclude an inner chamber disposed within the fluid collection chamber,the inner chamber bounded by the canister top, an inner wall and abottom end, wherein the second portions of the first and secondelectrodes are disposed within the inner chamber. At least a portion ofthe bottom end of the inner chamber may be formed of a water-solublefilm.

The present disclosure also relates to a portable negative pressurewound therapy apparatus including a dressing assembly for positioningover a wound to apply a negative pressure to the wound and a canisterassembly in fluid communication with the dressing assembly. The canisterassembly includes a control unit, a vacuum source disposed in thecontrol unit, a pressure sensor in communication with the control unit,and a collection canister. The collection canister includes an inletconduit in fluid communication with the dressing assembly, a chamber tocollect wound fluids from the dressing assembly, an inlet port coupledto the inlet conduit to introduce the wound fluids from the dressingassembly into the chamber, and a suction port to communicate with thechamber and the vacuum source. The canister assembly may also include atransducer port to communicate with the chamber and the pressure sensor.

The present disclosure also relates to a system for negative pressuretherapy in connection with healing a wound including a dressing assemblyfor positioning relative to a wound bed and a negative pressuremechanism. The negative pressure mechanism includes a control unit, acollection canister for collecting exudate removed from the wound bedunder negative pressure supplied by the control unit, and a detectorcircuit. The detector circuit includes first and second electricallyconductive contacts disposed within the collection canister and anindicator adapted to provide a perceptible indication when exudate makescontact with the first and second electrically conductive contacts. Thedetector circuit is open in the absence of exudate making contact withthe first and second electrically conductive contacts. The detectorcircuit is closed when exudate makes contact with the first and secondelectrically conductive contacts. The first and second electricallyconductive contacts may be mounted at a position within the collectioncanister corresponding to a maximum fill volume of the collectioncanister.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently disclosed negative pressure woundtherapy systems and sensors for use therein will become apparent tothose of ordinary skill in the art when descriptions of variousembodiments thereof are read with reference to the accompanyingdrawings, of which:

FIG. 1 is a schematic diagram of an embodiment of a negative pressurewound therapy system in accordance with the present disclosure;

FIG. 2 is a schematic diagram of an embodiment of a negative pressurewound therapy system including a canister assembly in accordance withthe present disclosure;

FIG. 3 is a schematic diagram of the canister assembly of the negativepressure wound therapy system illustrated in FIG. 2;

FIG. 4 is a cross-sectional view of the collection canister of thecanister assembly shown in FIG. 2 taken along the lines 4-4;

FIG. 5 is a cross-sectional view of the collection canister shown inFIG. 4 taken along the lines 5-5;

FIG. 6 is a bottom view of the collection canister top shown in FIG. 4;

FIG. 7 is a cross-sectional view of another embodiment of a collectioncanister in accordance with the present disclosure;

FIG. 8 is a cross-sectional view of yet another embodiment of acollection canister in accordance with the present disclosure;

FIGS. 9A through 9C are perspective views of embodiments of theelectrical contact protection unit of the collection canisterillustrated in FIG. 8, shown with varied geometric shapes, in accordancewith the present disclosure;

FIG. 10 is a schematic diagram of another embodiment of a collectioncanister in accordance with the present disclosure;

FIG. 11 is a cross-sectional view of yet another embodiment of acollection canister in accordance with the present disclosure;

FIG. 12 is a perspective view of the canister assembly of the negativepressure wound therapy system illustrated in FIG. 2 shown with a windowhaving fluid level markings in accordance with the present disclosure;

FIG. 13 is a schematic diagram of an embodiment of a detector circuit inaccordance with the present disclosure;

FIG. 14A is a schematic diagram of an embodiment of a detection circuitin accordance with the present disclosure; and

FIG. 14B is a schematic diagram of another embodiment of a detectioncircuit in accordance with the present disclosure.

DETAILED DESCRIPTION

Various embodiments of the present disclosure provide negative pressurewound therapy systems (or apparatus) including a collection canisterhaving a chamber to collect wound fluids. Embodiments of the presentlydisclosed negative pressure wound therapy systems are generally suitablefor use in applying negative pressure to a wound to facilitate healingof the wound in accordance with various treatment modalities.Embodiments of the presently disclosed negative pressure wound therapysystems are entirely portable and may be worn or carried by the usersuch that the user may be completely ambulatory during the therapyperiod. Embodiments of the presently disclosed negative pressure woundtherapy apparatus and components thereof may be entirely reusable or maybe entirely disposable after a predetermined period of use or may beindividually disposable whereby some of the components are reused for asubsequent therapy application.

Hereinafter, embodiments of the presently disclosed negative pressurewound therapy systems and embodiments of the presently disclosed sensorsfor use in negative pressure wound therapy systems will be describedwith reference to the accompanying drawings. Like reference numerals mayrefer to similar or identical elements throughout the description of thefigures. As used herein, “wound exudate”, or, simply, “exudate”,generally refers to any fluid output from a wound, e.g., blood, serum,and/or pus, etc. As used herein, “fluid” generally refers to a liquid, agas or both. As used herein, “transmission line” generally refers to anytransmission medium that can be used for the propagation of signals fromone point to another.

Referring to FIG. 1, a negative pressure wound therapy apparatusaccording to an embodiment of the present disclosure is depictedgenerally as 10 for use on a wound bed “w” surrounded by healthy skin“s”. Negative pressure wound therapy apparatus 10 includes a wounddressing 12 positioned relative to the wound bed “w” to define a vacuumchamber 14 about the wound bed “w” to maintain negative pressure at thewound area. Wound dressing 12 includes a contact layer 18, a woundfiller 20 and a wound cover 24.

Contact layer 18 is intended for placement within the wound bed “w” andmay be relatively non-supportive or flexible to substantially conform tothe topography of the wound bed “w”. A variety of materials may be usedfor the contact layer 18. Contact layer 18 selection may depend onvarious factors such as the patient's condition, the condition of theperiwound skin, the amount of exudate and/or the condition of the woundbed “w”. Contact layer 18 may be formed from perforated film material.The porous characteristic of the contact layer 18 permits exudate topass from the wound bed “w” through the contact layer 18. Passage ofwound exudate through the contact layer 18 may be substantiallyunidirectional such that exudate does not tend to flow back into thewound bed “w”. Unidirectional flow may be encouraged by directionalapertures, e.g., apertures positioned at peaks of undulations orcone-shaped formations protruding from the contact layer 18.Unidirectional flow may also be encouraged by laminating the contactlayer 18 with materials having absorption properties differing fromthose of the contact layer 18, or by selection of materials that promotedirectional flow. A non-adherent material may be selected for formingthe contact layer 18 such that the contact layer 18 does not tend tocling to the wound bed “w” or surrounding tissue when it is removed. Oneexample of a material that may be suitable for use as a contact layer 18is commercially available under the trademark XEROFLOW® offered by TycoHealthcare Group LP (d/b/a Covidien). Another example of a material thatmay be suitable for use as the contact layer 18 is the commerciallyavailable CURITY® nonadherent dressing offered by Tyco Healthcare GroupLP (d/b/a Covidien).

Wound filler 20 is positioned in the wound bed “w” over the contactlayer 18 and is intended to transfer wound exudate. Wound filler 20 isconformable to assume the shape of any wound bed “w” and may be packedup to any level, e.g., up to the level of healthy skin “s” or tooverfill the wound such that wound filler 20 protrudes over healthy skin“s”. Wound filler 20 may be treated with agents such aspolyhexamethylene biguanide (PHMB) to decrease the incidence ofinfection and/or other medicaments to promote wound healing. A varietyof materials may be used for the wound filler 20. An example of amaterial that may be suitable for use as the wound filler 20 is theantimicrobial dressing commercially available under the trademarkKERLIX™ AMD™ offered by Tyco Healthcare Group LP (d/b/a Covidien).

Cover layer 24 may be formed of a flexible membrane, e.g., a polymericor elastomeric film, which may include a biocompatible adhesive on atleast a portion of the cover layer 24, e.g., at the periphery 26 of thecover layer 24. Alternately, the cover layer 24 may be a substantiallyrigid member. Cover layer 24 may be positioned over the wound bed “w”such that a substantially continuous band of a biocompatible adhesive atthe periphery 26 of the cover layer 24 forms a substantially fluid-tightseal with the surrounding skin “s”. An example of a material that may besuitable for use as the cover layer 24 is commercially available underthe trademark CURAFORM ISLAND® offered by Tyco Healthcare Group LP(d/b/a Covidien).

Cover layer 24 may act as both a microbial barrier and a fluid barrierto prevent contaminants from entering the wound bed “w” and to helpmaintain the integrity thereof.

In one embodiment, the cover layer 24 is formed from a moisture vaporpermeable membrane, e.g., to promote the exchange of oxygen and moisturebetween the wound bed “w” and the atmosphere. An example of a membranethat may provide a suitable moisture vapor transmission rate (MVTR) is atransparent membrane commercially available under the trade namePOLYSKIN® II offered by Tyco Healthcare Group LP (d/b/a Covidien). Atransparent membrane may help to permit a visual assessment of woundconditions to be made without requiring removal of the cover layer 24.

Wound dressing 12 may include a vacuum port 30 having a flange 34 tofacilitate connection of the vacuum chamber 14 to a vacuum system.Vacuum port 30 may be configured as a rigid or flexible, low-profilecomponent and may be adapted to receive a conduit 36 in a releasable andfluid-tight manner. An adhesive on at least a portion of the undersideof the flange 34 may be used to provide a mechanism for affixing thevacuum port 30 to the cover layer 24. The relative positions, sizeand/or shape of the vacuum port 30 and the flange 34 may be varied froman embodiment depicted in FIG. 1. For example, the flange 34 may bepositioned within the vacuum chamber 14 such that an adhesive on atleast a portion of an upper side surface of the flange 34 affixes thevacuum port 30 to the cover layer 24. A hollow interior portion of thevacuum port 30 provides fluid communication between the conduit 36 andthe vacuum chamber 14. Conduit 36 extends from the vacuum port 30 toprovide fluid communication between the vacuum chamber 14 and the vacuumsource 40. Alternately, the vacuum port 30 may not be included in thedressing 12 if other provisions are made for providing fluidcommunication with the conduit 36.

Any suitable conduit may be used for the conduit 36, including conduitfabricated from flexible elastomeric or polymeric materials. In thenegative pressure wound therapy apparatus 10 illustrated in FIG. 1, theconduit 36 includes a first conduit section 36A, a second conduitsection 36B, a third conduit section 36C and a fourth conduit section360. The first conduit section 36A extends from the vacuum port 30 andis coupled via a fluid line coupling 100 to the second conduit section36B, which extends to the collection canister 38. The third conduitsection 36C extends from the collection canister 38 and is coupled viaanother fluid line coupling 100 to the fourth conduit section 360, whichextends to the vacuum source 40. The shape, size and/or number ofconduit sections of the conduit 36 may be varied from the first, second,third and fourth conduit sections 36A, 36B, 36C and 360 depicted in FIG.1.

The first, second, third and fourth conduit sections 36A, 36B, 36C and360 of the conduit 36 may be connected to components of the apparatus 10by conventional airtight means, such as, for example, friction fit,bayonet coupling, or barbed connectors. The connections may be madepermanent. Alternately, a quick-disconnect or other releasableconnection means may be used to provide some adjustment flexibility tothe apparatus 10.

Collection canister 38 may be formed of any type of container that issuitable for containing wound fluids. For example, a semi-rigid plasticbottle may be used for the collection canister 38. A flexible polymericpouch or other hollow container body may be used for the collectioncanister 38. Collection canister 38 may contain an absorbent material toconsolidate or contain the wound fluids or debris. For example, superabsorbent polymers (SAP), silica gel, sodium polyacrylate, potassiumpolyacrylamide or related compounds may be provided within collectioncanister 38. At least a portion of canister 38 may be transparent orsemi-transparent, e.g., to permit a visual assessment of the woundexudate to assist in evaluating the color, quality and/or quantity ofexudate. A transparent or semi-transparent portion of the collectioncanister 38 may permit a visual assessment to assist in determining theremaining capacity or open volume of the canister and/or may assist indetermining whether to replace the collection canister 38.

The collection canister 38 is in fluid communication with the wounddressing 12 via the first and second conduit sections 36A, 36B. Thethird and fourth conduit sections 36C, 360 connect the collectioncanister 38 to the vacuum source 40 that generates or otherwise providesa negative pressure to the collection canister 38. Vacuum source 40 mayinclude a peristaltic pump, a diaphragmatic pump or other suitablemechanism. Vacuum source 40 may be a miniature pump or micropump thatmay be biocompatible and adapted to maintain or draw adequate andtherapeutic vacuum levels. The vacuum level of subatmospheric pressureachieved may be in the range of about 20 mmHg to about 500 mmHg. Inembodiments, the vacuum level may be about 75 mmHg to about 125 mmHg, orabout 40 mmHg to about 80 mmHg. One example of a peristaltic pump thatmay be used as the vacuum source 40 is the commercially availableKangaroo PET Eternal Feeding Pump offered by Tyco Healthcare Group LP(d/b/a Covidien). Vacuum source 40 may be actuated by an actuator (notshown) which may be any means known by those skilled in the art,including, for example, alternating current (AC) motors, direct current(DC) motors, voice coil actuators, solenoids, and the like. The actuatormay be incorporated within the vacuum source 40.

In embodiments, the negative pressure wound therapy apparatus 10includes one or more fluid line couplings 100 that allow for selectablecoupling and decoupling of conduit sections. For example, a fluid linecoupling 100 may be used to maintain fluid communication between thefirst and second conduit sections 36A, 36B when engaged, and mayinterrupt fluid flow between the first and second conduit sections 36A,36B when disengaged. Thus, fluid line coupling 100 may facilitate theconnection, disconnection or maintenance of components of the negativepressure wound therapy apparatus 10, including the replacement of thecollection canister 38. Additional or alternate placement of one or morefluid line couplings 100 at any location in line with the conduit 36 mayfacilitate other procedures. For example, the placement of a fluid linecoupling 100 between the third and fourth conduit sections 36C, 360, asdepicted in FIG. 1, may facilitate servicing of the vacuum source 40.

Referring to FIG. 2, the negative pressure wound therapy system showngenerally as 200 includes a dressing assembly 210, a wound port assembly220, an extension assembly 230 and a canister assembly 240. Dressingassembly 210 is positioned relative to the wound area to define a vacuumchamber about the wound area to maintain negative pressure at the woundarea. Dressing assembly 210 may be substantially sealed from extraneousair leakage, e.g., using adhesive coverings. Wound port assembly 220 ismounted to the dressing assembly 210. For example, wound port assembly220 may include a substantially continuous band of adhesive at itsperiphery for affixing the wound port assembly 220 to the dressingassembly 210. Extension assembly 230 is coupled between the wound portassembly 220 and the canister assembly 240 and defines a fluid flow pathbetween the wound port assembly 220 and the canister assembly 240. Ahollow interior of the wound port assembly 220 provides fluidcommunication between the extension assembly 230 and the interior of thedressing assembly 210. Dressing assembly 210 and the wound port assembly220 shown in FIG. 2 are similar to components of the wound dressing 12of FIG. 1 and further description thereof is omitted in the interests ofbrevity.

Canister assembly 240 includes a control unit 246 and a collectioncanister 242 disposed below the control unit 246. Control unit 246 andthe collection canister 242 may be releasably coupled. Mechanisms forselective coupling and decoupling of the control unit 246 and thecollection canister 242 include fasteners, latches, clips, straps,bayonet mounts, magnetic couplings, and other devices. Collectioncanister 242 may consist of any container suitable for containing woundfluids.

In one embodiment, the negative pressure wound therapy system 200 iscapable of operating in a continuous mode or an alternating mode. In thecontinuous mode, the control unit 246 controls a pump (e.g., suctionpump 360 shown in FIG. 3) to continuously supply a selected vacuum levelat the collection canister 242 to create a reduced pressure state withinthe dressing assembly 210. In the alternating mode, the control unit 246controls the pump to alternating supply a first negative pressure, e.g.,about 80 mmHg, at the collection canister 242 for a preset fixed amountof time and a second negative pressure, e.g., about 50 mmHg, at thecollection canister 242 for a different preset fixed amount of time.

In general, the output of the pump is directly related to the degree ofair leakage in the negative pressure wound therapy system 200 and theopen volume in the collection canister 242. If there is sufficient airleakage in the system 200, e.g., at the dressing assembly 210, the pumpcan remain on continuously and the control unit 246 can control negativepressure at the collection canister 242 by adjusting the pump speed.Alternatively, if there is not sufficient air leakage in the system 200to permit the pump to remain on continuously, the control unit 246 cancontrol negative pressure at the collection canister 242 by turning thepump on and off, e.g., for non-equal on/off periods of time.

Control unit 246 responds to various sensed events by signaling alarms.Various types of conditions may be signaled by alarms. In embodiments,control unit 246 is capable of signaling alarms for failed pressuresensor condition, use odometer expired condition, watchdog resetcondition, failed pump condition, leak condition, replace canistercondition, excessive vacuum condition, failed LEDs condition, lowbattery condition, very low battery condition, and failed batterycondition. Priority levels may be associated with alarms. Inembodiments, the priority levels of alarms are low priority alarm,medium priority alarm, and system alarm (highest priority). Low priorityalarms, when triggered, may be continuously indicated. Medium priorityalarms and system alarms, when triggered, may have a flashingindication.

Control unit 246 may stop operation of the pump (e.g., suction pump 360shown in FIG. 3) in response to an alarm, e.g., depending on alarm typeand/or priority level. In embodiments, the control unit 246 stopsoperation of the pump in response to system alarms, e.g., failedpressure sensor system alarm, use odometer expired system alarm,watchdog reset system alarm, failed pump system alarm, excessive vacuumsystem alarm, and/or failed LEDs system alarm.

If an air leak develops in the negative pressure wound therapy system200, e.g., at the dressing assembly 210, for which the control unit 246cannot compensate by increasing the pump speed, the control unit 246 mayindicate an alarm. For example, the control unit 246 may indicate a leakalarm after two consecutive minutes of operation in which the vacuumlevel is below the current set point (or below the minimum level of aset point range).

Audible indicatory means may also be incorporated or associated with thecontrol unit 246 to notify the user of a condition, e.g., leak, canisterassembly tip, failed pressure sensor, failed pump, excessive vacuum, orlow battery conditions. The audio indication for some alarm types can bepaused by pressing a pause alarm button (not shown).

In embodiments, the control unit 246 includes a user interface (notshown). Control unit 246 also includes a processor (e.g., 310 shown inFIG. 3). A pressure transducer (e.g., transducer 340 shown in FIG. 3) iselectrically coupled to the processor. The user turns ON the canisterassembly 240 by pressing a power button (not shown). When the powerbutton is pressed, the control unit 246 performs a series of internalchecks during power up. In one embodiment, after successfully completingthe power-up tasks, the control unit 246 turns on the pump 360 using thestored settings. At initial activation of the canister assembly 240, thestored settings are the default settings. In one embodiment, the defaultsettings for controlling the pump 360 are 80 mmHg and continuous mode.In one embodiment, the currently stored vacuum level setting can bealtered by the user, e.g., to 50 mmHg. In one embodiment, the currentlystored mode setting can be altered by the user, e.g., to an alternatingmode.

Canister assembly 240 may be constructed from a variety of materialssuch as Lucite™ polycarbonate, metals, metal alloys, plastics, or otherdurable materials capable of withstanding forces applied during normaluse, and may have some capability of withstanding possibly excessiveforces resulting from misuse. Collection canister 242 may include awindow (e.g., 1223 shown in FIG. 12) with fluid level markings orgraduations (e.g., 1225 shown in FIG. 12) for promoting visualassessment of the amount of exudate contained within the collectioncanister 242. A transparent or partially transparent collection canister242 may thus assist in determining the remaining capacity of thecollection canister 242 and/or when the collection canister 242 shouldbe replaced.

Referring to FIG. 3, an embodiment of the canister assembly 240illustrated in FIG. 2 is shown and includes a control unit 246 and acollection canister 242. In embodiments, canister assembly 240 iscoupled via an extension assembly 230 to a dressing assembly (e.g.,wound dressing 12 shown in FIG. 1) to apply negative pressure to a woundto facilitate healing of the wound in accordance with various treatmentmodalities.

Control unit 246 includes a suction pump 360, a pump inlet conduit 372,a pump outlet conduit 362, a first filter element 376, a transducer 340,a transducer conduit 352, a second filter element 354, a firstconnecting channel 378 and a second connecting channel 356.

Suction pump 360 may provide negative pressure produced by a pistondrawn through a cylinder. Suction pump 360 may be a peristaltic pump ora diaphragm pump. Suction pump 360 may be a manual pump or an automatedpump. The automated pump may be in the form of a portable pump, e.g., asmall or miniature pump that maintains or draws adequate and therapeuticvacuum levels. In one embodiment, the suction pump 360 is a portable,lightweight, battery-operated, DC motor-driven pump. A vibration dampingtape (not shown), e.g., viscoelastic damping tape, may be applied to theouter surface of the suction pump 360 to reduce vibration and itsassociated noise. Suction pump 360 may be contained within its ownsub-housing (not shown), which may be formed substantially entirely ofmolded foam, e.g., used as a silencer to provide sound mitigation byreducing the sound energy of the expelled air during operation of thesuction pump 360, and may include a carbon loaded foam. Suction pump 360provides negative pressure within the chamber 335 of the collectioncanister 242 by drawing air through the suction port 374.

Pump inlet conduit 372 provides fluid communication between the suctionpump 360 and the first filter element 376. The first filter element 376may include one or more filters and is configured to substantiallyprevent entry of exudate into the suction pump 360. In embodiments, thecontrol unit 246 stops operation of the suction pump 360 when the firstfilter element 376 becomes occluded. A variety of filters can be usedfor the first filter element 376. In one embodiment, the first filterelement 376 includes a hydrophobic filter that substantially preventsfluids from entering into the suction pump 360 and potentially causingdamage to electronics or pneumatic components. Exhaust air from the pump360 is vented through an exhaust port (not shown) via the pump outletconduit 362. Pump outlet conduit 362 may be coupled to one or morefilters (not shown) for filtering the exhaust air from the pump 360.

Transducer 340 is in fluid communication with the collection canister242 to detect the vacuum level within the collection canister 242. Inembodiments, the transducer 340 generates an electrical signal thatvaries as a function of vacuum level within the collection canister 242,and the signal is communicated to the processor 310. Logic associatedwith the transducer 340 and the pump 360 may reduce the speed of thepump 360 or stop operation of the pump 360 in response to the vacuumlevel detected by the transducer 340. Any suitable device capable ofdetecting pressure may be utilized for the transducer 340, including,but not limited to, a pressure switch, transducer or transmitter.Transducer conduit 352 provides fluid communication between thetransducer 340 and the second filter element 354. In one embodiment, thesecond filter element 354 is a hydrophobic filter that substantiallyprevents fluid contamination of the transducer 340.

First connecting channel 378 provides fluid communication between thefirst filter element 376 and the suction port 374, when the control unit246 and the collection canister 242 are operably coupled to each other.Second connecting channel 356 provides fluid communication between thesecond filter element 354 and the transducer port 396, when the controlunit 246 and the collection canister 242 are operably coupled to eachother. First connecting channel 378 may be coupled to a control suctionport (not shown) located on the bottom side of the control unit 246 andconfigured to engage with the suction port 374 located on the collectioncanister top 336 when the control unit 246 and the collection canister242 are joined together. Second connecting channel 356 may be coupled toa control unit transducer port (not shown) located on the bottom side ofthe control unit 246 and configured to engage with the transducer port396 located on the collection canister top 336 when the control unit 246and the collection canister 242 are joined together.

Control unit 246 also includes a processor 310. In embodiments, theprocessor 310 is electrically coupled via a transmission line 341 to thetransducer 340 and electrically coupled via a transmission line 361 tothe suction pump 360. Processor 310 may include any type of computingdevice, computational circuit, or any type of processor or processingcircuit capable of executing a series of instructions that are stored ina memory (not shown) of the control unit 246. The series of instructionsmay be transmitted via propagated signals for execution by processor 310for performing the functions described herein and to achieve a technicaleffect in accordance with the present disclosure. Control unit 246 mayalso include a user interface (not shown).

Canister assembly 240 also includes a sensor 320. Sensor 320 may includean electrode pair (e.g., 325A, 325B shown in FIG. 4). In embodiments,the sensor 320 is used to measure resistance, capacitance or voltage toprovide feedback to the processor 310 indicative of a condition. Inembodiments, an electric circuit 328 is electrically coupled via atransmission line 321 between the sensor 320 and the processor 310.Electric circuit 328 is configured to detect an electrical propertyassociated with the sensor 320 and may include various components. Someexamples of circuits that may be suitable for use as the electriccircuit 328 are illustrated in the circuit diagrams 1401,1402 and 1403shown in FIGS. 14A, 14B and 14C, respectively. Although the electriccircuit 328 is shown as a separate circuit in FIG. 3, it may beincorporated into the sensor 320, the processor 310, or other component,e.g., a printed circuit board (not shown) associated with the processor310. Sensor 320 may include multiple electrode pairs (e.g., 325A, 325Band 325C, 3250 shown in FIG. 11). In embodiments, any change in theresistance, capacitance or voltage feedback occurring when theelectrodes are simultaneously in contact with exudate in the collectioncanister 242 is used to indicate a condition, such as, for example, areplace-collection-canister condition or full-collection-canistercondition.

Collection canister 242 includes a canister top 336, a chamber 335 tocollect wound fluids from the dressing assembly, a suction port 374 tocommunicate with the chamber 335 and the suction pump 360, a canisterinlet port 334 coupled to the extension assembly 230 to introduce thewound fluids from the dressing assembly into the chamber 335, and atransducer port 396 to communicate with the chamber 335 and thetransducer 340. Collection canister 242 may be disposable. Canisterinlet port 334 may be connectable with the extension assembly 230 byconventional air and fluid tight means, such as those described above.In embodiments, canister inlet port 334 may contain a luer lock or otherconnector within the purview of those skilled in the art to secure theend of the extension assembly 230 with the canister inlet port 334.Canister inlet port 334 may be configured to receive a cap for use toprevent leakage of exudate and odor from the chamber 335 when thecollection canister 242 is separated from the control unit 246.

Referring to FIG. 4, an embodiment of the collection canister 242 of thecanister assembly 240 illustrated in FIG. 3 is shown and includes thecollection canister top 336, the chamber 335, which has length “L1”, thecanister inlet port 334, the suction port 374, and the transducer port396. The sensor 320 of FIG. 3 includes is shown as an electrode pair325A, 325B in FIG. 4. In embodiments, an electric potential (or voltage)is applied to the electrodes 325A, 325B. When a voltage is supplied andthe electrodes 325A, 325B are simultaneously in contact with an ionicfluid, e.g., exudate, electric current flows via an electro-chemicalreaction that occurs between the ions in the fluid and the electricallypolarized electrodes 325A, 325B.

In embodiments, one or more electrode pairs (e.g., 325A, 325B shown inFIG. 4) is coupled to an electric circuit (e.g., 328 shown in FIG. 3),which is configured to detect an electrical properly associated with theelectrode pair(s). In embodiments, a measurement of the change involtage across the electrode pair(s) as a result from the flow ofcurrent is used to activate an indicator (e.g., 1358 shown in FIG. 13)as notification to the user of a condition. For example, an indicatormay be activated to notify the user that the collection canister 242 isfull, which may be referred to as the full-collection-canistercondition. An indicator may be activated to notify the user that it istime to replace the collection canister 242, which may be referred to asthe replace collection-canister condition. The occurrence of areplace-collection-canister condition does not necessarily indicate thatthe chamber 335 is full of exudate. Rather, a replacecollection-canister condition may indicate that a volume of exudate(less than the volume of the chamber 355) has been collected. Usernotification of a replace collection-canister condition may thus providesome flexibility to the user in the timing of the replacement oremptying of the collection canister 242, by allowing an additional timeperiod of operation before the volume of the collected exudate reachesthe maximum volume capacity of the chamber 355.

Referring to FIG. 5, a cross-sectional view of the collection canister242 illustrated in FIG. 4 is shown and includes the collection canistertop 336, the chamber 335, and the two electrodes 325A, 325B. Electrodes325A, 325B include a first portion 322, 324 and a second portion 321,323, respectively, wherein the first portions 322, 324 have a firstdiameter “D1” and the second portions 321, 323 have a second diameter“D2”, which is smaller than the first diameter “D1”. In an embodiment,the first portions 322, 324 are supported by the surface “S” of thecollection canister top 336. In an alternative embodiment, the firstportions 322, 324 are arranged to be substantially flush with thesurface “S” of the collection canister top 336. Each of the secondportions 321, 323 extends downwardly from the collection canister top336 through a corresponding hole in the collection canister top 336 andinto the chamber 335. Electrodes 325A, 325B, or portions thereof,include electrically conductive material, e.g., metal or metal alloy.Electrodes 325A, 325B, or portions thereof, may include an electricallyconductive coating. For example, electrodes 325A, 325B, or portionsthereof, may be plated with an electrically conductive metallic layer.The relative positions, size and/or shape of the two electrodes 325A,325B may be varied from an embodiment depicted in FIG. 5.

In embodiments, two probe contacts (not shown) are located at the bottomside of the control unit 246 and positioned to make electrical contactwith the first portions 322, 324 of the electrodes 325A, 325B,respectively, when the collection canister 242 and the control unit 246are connected to each other.

FIG. 6 is a bottom view of the collection canister top 336 illustratedin FIG. 4 shown with the canister inlet port 334, the suction port 374,the transducer port 396 and the two electrodes 325A, 325B. The relativepositions, size and/or shape of the canister inlet port 334, the suctionport 374 and the transducer port 396 may be varied from an embodimentdepicted in FIGS. 4 and 6.

Referring to FIG. 7, an embodiment of a collection canister 742 is shownand includes a collection canister top 736 and a chamber 735. Collectioncanister 742 is similar to the collection canister 242 illustrated inFIGS. 4 and 5. Collection canister 742 includes two electrodes with afirst portion 722, 724 and a second portion 721, 723, respectively,which are similar to the two electrodes 325A, 325B shown in FIG. 4,except that the second portions 721, 723 of FIG. 7 are substantiallycovered by a coating “C”. In alternative embodiments, coating “C” coversa section of the second portions 721, 723, such as the tip section “T”.

In embodiments, the coating “C” is a water-soluble coating for theprotection of the second portions 721, 723 and may have a predeterminedamount of time in contact with fluid before the coating dissolves.Coating “C” may inhibit encrustation of the second portions 721, 723formed by the drying of exudate. For example, the coating “C” mayinhibit encrustation by affecting the formation and binding of proteinsor may decrease wettability of the second portions 721, 723 and allowliquid to shed.

Coating “C” may help to minimize the amount of time that fluid in thechamber 735 of the collection canister 742 comes into contact with thesecond portions 721,723, e.g., during accidental tip over of thecanister assembly (e.g., 240 shown in FIG. 12) or during ambulationwhile the canister assembly is worn or carried by the user. Inembodiments, the coating “C” is characterized by a predetermined amountof time in contact with fluid before the coating “C” dissolves. Thepredetermined amount of time may be a short period of time, e.g., aboutone hour to about ten hours, which may be suitable in the case of a highrate of flow of exudate from the wound into the chamber 735. Thepredetermined amount of time may be a long period of time, e.g., aboutforty-eight hours, which may be suitable in the case of a low rate offlow of exudate into the chamber 735. The predetermined amount of timein contact with fluid before the coating “C” dissolves may be variedfrom the above-mentioned time periods. In some cases, depending oncharacteristics of the fluid to be collected in the collection canister742, the coating “C” may be configured to dissolve at a predeterminedrate, e.g., based on the thickness, density and/or composition of thecoating “C”.

Referring to FIG. 8, an embodiment of a collection canister 842 is shownand includes a collection canister top 836 and a fluid collectionchamber 835 having a width “W1”. Collection canister 842 also includesthe two electrodes 325A, 325B shown in FIGS. 4 and 5. Collectioncanister 842 is similar to the collection canister 242 illustrated inFIGS. 4 and 5, except that the two electrodes 325A, 325B are disposedwithin an electrical contact protection unit bounded by the collectioncanister top 836, an inner wall 880 and a bottom end “F”. The electricalcontact protection unit may be formed in various sizes and shapes, suchas, for example, the shapes shown in FIGS. 9A, 9B and 9C.

In embodiments, the bottom end “F”, or portion thereof, is formed of awater soluble film, which is configured to dissolve over a period oftime. In embodiments, the water soluble film dissolves over a period oftime depending on characteristics of the water soluble film, e.g.,thickness, density and/or composition of the water soluble film,characteristics of the fluid contained in the fluid collection chamber,e.g., pH, viscosity and/or ionic composition of the fluid, and/or therate of flow of the fluid into the fluid collection chamber 835.

Referring to FIGS. 9A through 9C, embodiments of the electrical contactprotection unit of the collection canister 842 illustrated in FIG. 8 areshown with varied geometric shapes. Each of the electrical contactprotection units shown in FIGS. 9A through 9C includes an inner wall 880and a bottom end “F”, and each has a width (or maximum width) “W2” thatis less than the width “W1” of the fluid collection chamber 835 shown inFIG. 8. The electrical contact protection units shown in FIGS. 9A and 9Chave a length “L2”, which is less than the length “L1” of the chamber335 of the canister 242 shown in FIGS. 4 and 5. The relative positions,size and/or shape of the electrical contact protection units may bevaried from embodiments depicted in FIGS. 8 through 9C.

Referring to FIG. 10, an embodiment of a collection canister 1042 isshown and includes a collection canister top 1036 and a chamber 1035.Collection canister 1042 also includes the two electrodes 325A, 325Bshown in FIGS. 4 and 5. Collection canister 1042 is similar to thecollection canister 242 illustrated in FIGS. 4 and 5, except that thetwo electrodes 325A, 325B are disposed within a baffle unit formed oftwo baffle members 1050A, 1050B. Baffle members 1050A, 1050B may beformed in various sizes and shapes.

Referring to FIG. 11, an embodiment of a collection canister 1142 isshown and includes a collection canister top 1136, a chamber 1135, afirst electrode pair 1125A, 1125B and a second electrode pair 1125C,1125D. In one embodiment, a measurement of the change in voltage acrossthe first electrode pair 1125A, 1125B is used to activate an indicatoras notification to the user of a replace-collection-canister condition,and a measurement of the change in voltage across the second electrodepair 1125C, 1125D is used to activate an indicator as notification tothe user of a full collection canister condition.

Referring to FIG. 12, the canister assembly 240 of the negative pressurewound therapy system illustrated in FIG. 2 is shown and includes thecollection canister 242 shown with a transparent or semi-transparentportion 1223. Transparent or semitransparent portion 1223 includes fluidlevel markings or graduations 1225 and may help to permit a visualassessment of the amount of exudate contained within the collectioncanister 242, and, thus, may assist in determining the remainingcapacity of the collection canister 242 and/or when the collectioncanister 242 should be replaced or emptied. Transparent orsemi-transparent portion 1223 may help to permit a visual assessment ofthe wound exudate to assist in evaluating the color, quality and/orquantity of exudate.

Referring to FIG. 13, an embodiment of a detector circuit 1350 is shownand includes a sensor 1352, incorporating electrically conductivecontacts 1354 and 1356, and indicator unit 1358. Contacts 1534 and 1356may be disposed within the collection canister 242 at a pre-determinedheight or level within the collection canister 242 corresponding to atargeted volume of fluid or exudate accumulated within the collectioncanister 242. For example, contacts 1354 and 1356 may be positionedwithin the collection canister 242 at a position corresponding to themaximum fill volume of collection canister 122.

As illustrated in FIG. 13, contacts 1354 and 1356 of sensor 1352 arelaterally spaced. Contacts 1354 and 1356 are connected via transmissionlines 1362 to the indicator unit 1352 and power source 1360. Alkalinebatteries, wet cell batteries, dry cell batteries, nickel cadmiumbatteries, lithium batteries, NiMH batteries (nickel metal hydride),solar energy and other energy sources may serve as the power 1360. Powersource 1360 may be a separate unit from the power source utilized toenergize the vacuum source (e.g., 360 shown in FIG. 3).

In embodiments, the indicator unit 1358 of the detector circuit 1350generates an alert or signal that the canister 242 is full of a fluid,e.g., exudate. Indicator unit 1358 may be any type of indicator capableof alerting the user or clinician that the canister 242 needs to bereplaced. Indicator unit 1358 may be an audio and/or visual indicator.In an embodiment, the indicator unit 1358 includes an alarm or outputcomponent 1364, which includes logic or circuitry to generate a signalwhen power is provided to the indicator unit 1358. Output component 164is adapted to provide a perceptible sensory alert, which may be anaudio, visual, or other sensory alarm. In one embodiment, the indicator1358 is adapted to generate an audio signal and the output component1364 includes an audio circuit with a speaker. In one embodiment, theindicator 1358 is adapted to generate a visual signal and the outputcomponent 1364 includes a light source, such as a light-emitting diode(LED).

FIGS. 14A and 14B are schematic diagrams of detection circuits 1401,1402, respectively, for use to detect a voltage measurement across anelectrode pair, e.g., the electrodes 325A, 325B shown in FIGS. 4 and 5.Detection circuit 1401 includes a first resistor R1 and a secondresistor R2. In an embodiment, wherein the first resistor R1 is a10000000 ohm (10000K or 10 M) resistor, the second resistor R2 is a 24 Mohm resistor, and V1N equals 3.3V, the detection circuit 1401 mayproduce a constant 2.4V output (VOUT) when no exudate has shorted thetwo electrodes 325A, 325B.

Referring to FIG. 14B, the detection circuit 1402 includes a resistor R1and a capacitor C1. In an embodiment, wherein the resistor R1 is a100000 ohm (100K) resistor, the capacitor C1 is a 100 pf capacitor, andV_(IN) equals 3.3V, the detection circuit 1402 may produce a constant3.3V output (V_(OUT)) when no exudate has shorted the two electrodes325A, 325B.

In the detection circuits 1401 and 1402, when the two electrodes 325A,325B make contact with an ionic fluid, e.g., exudate, electric currentflows via an electrochemical reaction that occurs between the ions inthe fluid and the electrically polarized electrodes 325A, 325B,resulting in a change in the measured voltage output (V_(OUT)). Inembodiments, a measurement of the change in voltage across the electrodepair(s) as a result from the flow of current is used to activate anindicator (e.g., 1358 shown in FIG. 13) as notification to the user toreplace or empty the collection canister (e.g., 242 shown in FIGS. 4 and5).

Although embodiments of the present disclosure have been described indetail with reference to the accompanying drawings for the purpose ofillustration and description, it is to be understood that the inventiveprocesses and apparatus are not to be construed as limited thereby. Itwill be apparent to those of ordinary skill in the art that variousmodifications to the foregoing embodiments may be made without departingfrom the scope of the disclosure.

1.-17. (canceled)
 18. A negative pressure wound therapy system,comprising: a collection canister comprising a chamber configured tocollect wound fluids; a sensor configured to detect a conditionassociated with the collection canister, the sensor comprising: a firstelectrode including a first portion and a second portion, wherein thefirst portion of the first electrode is supported by a surface of thecollection canister, and the second portion of the first electrodeextends into the chamber; a second electrode including a first portionand a second portion, wherein the first portion of the second electrodeis supported by a surface of the collection canister, and the secondportion of the second electrode extends into the chamber; wherein achange in resistance, capacitance, or voltage in the first and secondelectrodes indicates the condition associated with the collectioncanister; and an inner wall disposed within the chamber, wherein thesecond portions of the first and second electrodes are disposed withinan area between a top portion of the collection canister and the innerwall.
 19. The negative pressure wound therapy system of claim 18,wherein the inner wall is configured to: deflect the wound fluid fromcontacting the first and second electrodes when the collection canisteris tilted, and allow the wound fluid to contact the first and secondelectrodes when the chamber is substantially full.
 20. The negativepressure wound therapy system of claim 18, wherein the inner wall isintegral to and not removable from the chamber.
 21. The negativepressure wound therapy system of claim 18, wherein the area between thetop portion of the collection canister and the inner wall is configuredto be filled with the wound fluid when the collection canister issubstantially full with the wound fluid.
 22. The negative pressure woundtherapy system of claim 18, further comprising a control unit.
 23. Thenegative pressure wound therapy system of claim 22, further comprising apressure sensor in communication with the control unit.
 24. The negativepressure wound therapy system of claim 22, wherein the control unit isconfigured to monitor and control a negative pressure within thecollection canister.
 25. The negative pressure wound therapy system ofclaim 18, further comprising a vacuum source and a suction portconfigured to communicate with the chamber and the vacuum source. 26.The portable negative pressure wound therapy system of claim 18, whereinthe collection canister comprises an inlet conduit.
 27. The negativepressure wound therapy system of claim 18, further comprising a circuitconfigured to detect an electrical property associated with the firstand second electrodes.
 28. The negative pressure wound therapy system ofclaim 18, wherein the condition in the collection canister comprises areplace-collection-canister condition or a full-collection-canistercondition.
 29. The negative pressure wound therapy system of claim 18,wherein the condition in the collection canister is indicated when thefirst and second electrodes are simultaneously in contact with fluid inthe collection canister.
 30. A negative pressure wound therapy system,comprising: a collection canister comprising a chamber configured tocollect wound fluids; a sensor configured to detect a conditionassociated with the collection canister, the sensor comprising: a firstelectrode including a first portion and a second portion, wherein thefirst portion of the first electrode is supported by a surface of thecollection canister, and the second portion of the first electrodeextends into the chamber; a second electrode including a first portionand a second portion, wherein the first portion of the second electrodeis supported by a surface of the collection canister, and the secondportion of the second electrode extends into the chamber; wherein achange in resistance, capacitance, or voltage in the first and secondelectrodes indicates the condition associated with the collectioncanister; wherein the first portion of the first and second electrodescomprise a first diameter and a rounded end and the second portion ofthe first and second electrodes comprise a second diameter and acylindrical shape, wherein the first diameter is larger than the seconddiameter.
 31. The negative pressure wound therapy system of claim 30,further comprising an inner wall disposed within the chamber, whereinthe second portions of the first and second electrodes are disposedwithin an area between a top portion of the collection canister and theinner wall.
 32. The negative pressure wound therapy system of claim 31,wherein the inner wall is configured to: deflect the wound fluid fromcontacting the first and second electrodes when the collection canisteris tilted, and allow the wound fluid to contact the first and secondelectrodes when the chamber is substantially full.
 33. The negativepressure wound therapy system of claim 31, wherein the inner wall isintegral to and not removable from the chamber.
 34. The negativepressure wound therapy system of claim 31, wherein the area between thetop portion of the collection canister and the inner wall is configuredto be filled with the wound fluid when the collection canister issubstantially full with the wound fluid.
 35. The negative pressure woundtherapy system of claim 30, further comprising a control unit.
 36. Thenegative pressure wound therapy system of claim 35, further comprising apressure sensor in communication with the control unit.
 37. The negativepressure wound therapy system of claim 35, wherein the control unit isconfigured to monitor and control a negative pressure within thecollection canister.
 38. The negative pressure wound therapy system ofclaim 30, further comprising a vacuum source and a suction portconfigured to communicate with the chamber and the vacuum source. 39.The negative pressure wound therapy system of claim 30, wherein thecollection canister comprises an inlet conduit.
 40. The negativepressure wound therapy system of claim 30, further comprising a circuitconfigured to detect an electrical property associated with the firstand second electrodes.
 41. The negative pressure wound therapy system ofclaim 30, wherein the condition in the collection canister comprises areplace-collection-canister condition or a full-collection-canistercondition.